Circuit breaker with high and low overcurrent means for disengaging the latch



July 26, 1966 N. R. BEAUDOIN 3,263,045

CIRCUIT BREAKER WITH HIGH AND LOW OVERCURRENT MEANS FOR DISENGAGING THE LATCH 5 Sheets-Sheet 1 Filed May 28, 1964 NORMAN R. BEAUDOIN BY WM] C ATTORNEY y 25, 1966 N. R. BEAUDOIN 3,263,045

CIRCUIT BREAKER WITH HIGH AND LOW OVERGURRENT MEANS FOR DISENGAGING THE LATCH Filed May 28, 1964 3 Sheets-Sheet 2 INVENTOR. NORMAN R. BEAUDOIN ATTORNEY July 26, 1966 N. R. BEAUDOIN 3,263,045

CIRCUIT BREAKER WITH HIGH AND LOW OVERCURRENT MEANS FOR DISENGAGING THE LATCH Filed May 28, 1964 5 Sheets-Sheet 5 F|G.4 I 22 I NVENTOR. NORMAN R. BEAUDOIN ATTORNEY United States Patent CIRCUIT BREAKER WITH HIGH AND LOW OVER- CURRENT MEANS FOR DISENGAGING THE LATCH I Norman R. Beaudoin, Southington, Conn., assignor to General Electric Company, a corporation of New York Filed May 28, 1964, Ser. No. 370,970 12 Claims. (Cl. 200-88) My invention relates to electric circuit breakers, and particularly to an improved latching-contact-bar type operating mechanism for small, manually-operable, currentresponsively tripped air circuit breakers for use in residential and commercial service entrance installations to control lighting and power circuits.

In order that small air circuit breakers may be economically used in service entrance and other distribution panel boards, it is necessary that the individual breakers be of simple and inexpensive construction andadapted to low cost, large scale assembly with a minimum number of inexpensive parts. On the other hand, such breakers must be strong, dependable and long-lasting in operation despite extended periods of non-use. They must provide dependable circuit breaking action in both manual and automatic operation and accurate overload response despite long periods of inactivity. For maximum utilization of space in a panel, the operating mechanism of such a breaker should be oriented so as to have its greatest dimension in the front-to-rear direction.

Accordingly, it is a principal object of my invention to provide a simple, inexpensive operating mechanism for an electric circuit breaker.

It is another object of my invention to provide such a mechanism which is oriented so as to have its greatest dimension in the front-to-rear direction of the breaker.

It is still another object of my invention to provide such a mechanism which has a relatively low latch pressure, so as to provide dependable current-responsive action.

It is a further object of my invention to provide such a mechanism whichis self-resetting.

Further objects and advantages of my invention will be apparent to those skilled in the art from the following detailed specification taken in conjunction with the accompanying drawings.

In carrying out my invention, in one preferred embodiment thereof, I provide a casing of suitable molded plastic insulating material integrally formed to provide means for mounting all operative parts of the breaker in cooperating relation. The circuit breaker mechanism comprises a contact arm which is relcasably supported at one end by an intermediate latch or pivot-support member for pivotal movement. A movable contact member is pivotally supported on the other end of the contact arm and includes a first section extending toward the first end of the contact arm and a second section extending away from the first end of the contact arm. A spring is mounted between the casing .and the first section of the contact member to bias the contact member for rotation about its pivotal mounting, and means is provided for limiting rotation of the contact member with respect to the contact arm so that the spring at times will move the contact arm and the contact member as a unit between open and closed circuit positions.

As the contact arm and contact member move from the open circuit to the closed circuit position the spring holds the first section of the contact member against the stop member so that the contact member moves as a unit until the second section of the contact arm engages a stationary contact mounted in the casing. Further movement of the contact arm causes the first section of the contact member to be disengaged from the stop member and further compresses the spring so that the spring biases the contact occurrence of pre-determined conditions.

member for rotation about its pivotal mounting on the contact arm, thus providing latch pressure between the contact member and the stationary contact. When the contact arm is initially moved toward the open circuit position the spring causes the contact member to pivot about its pivotal mounting until the first section of the contact member engages the stop member, after which the spring causes the contact arm and contact member to move as a unit toward the open circuit position.

In carrying out my invention in one term, I provide means for moving the contact arm and contact member between the open circuit and closed circuit positions comprising a link member pivotally connected to the contact arm. The end of the link member remote from the contact arm is connected to a manually movable handle. The handle includes an arcuate portion which is mounted in a slot in the casing and a lever portion which extends through an aperture in the casing to provide an element to be grasped by the user. By means of this arrangement, the mechanism as a whole is oriented within the casing so that it has its greatest dimension in the front-torear direction.

Novel current-responsive means is also provided in accordance with the invention for holding the member normally in a stationary position, and releasing it upon the The tripping mechanism is responsive to both relatively low overcurrent conditions and to relatively high overcurrent conditions to free the intermediate latch or pivot support member and thereby disengage the first end of the contact arm so that the spring will move the contact arm and contact member as a unit to the open circuit position.

The current-responsive tripping mechanism includes a latch which engages the pivot support member with a predetermined amount of latch overlap, and a spaced fixedly mounted bimetallic strip member. A coupling member is slidably mounted on the latch and extends beyond the bimetallic strip member to operatively connect the bimetallic strip member to the latch member. A flat spring is mounted on the latch member around the coupling member and also engages the pivot support member. The position of the latch member is determined by the predetermined amount of latch overlap provided. The position of the bimetal is determined by its fixed mounting. The flat spring has a dual purpose in that it causes the coupling member to operatively engage the bimetal member despite variations in their positions and also returns the pivot support member to its normal position after automatic operation of the circuit breaker.

In the drawings:

FIGURE 1 is an elevational view of a circuit breaker embodying my invention, one side of the casing being removed to show the circuit breaker mechanism in the open circuit position;

FIGURE 2 is an elevational view similar to FIGURE 1,

but showing a mechanism in the closed circuit position;

FIGURE 3 is an exploded view in perspective of the circuit breaker of FIGURE 1;

FIGURE 4 is an elementary mechanical diagram illustrating the movable contact mechanism in the open circuit position;

FIGURE 5 is an elementary mechanical diagram illustrating the movable contact member moving toward closed position with the contact member j-ust engaging the stationary contact;

FIGURE 6 is an elementary mechanical diagram showing the movable contact mechanism in the closed circuit position; and

FIGURE 7 is an elementary mechanical diagram showing the movable contact mechanism in the tripped position.

Referring now to the drawings and particularly to FIGURES 1-3, the circuit breaker 10 there illustrated is disposed in a simple casing 11 which is preferably formed of a suitable molded plastic insulating material. The breaker comprises a plug in type line terminal clip 12 mounted with a slot 13 in the lower wall of the casing 111, and a screw-type load terminal member 14 mounted in a slot 15 in an end wall of the casing. The line terminal clip 12 is shown in position on a bus bar 16 forming part of a suitable panelboard base (not shown).

The electrical circuit between the line and load terminals includes a pair of separable switch contacts 17 and 18. The contact 17 is fixedly mounted on one arm of the line terminal clip 12 and the contact 18 is mounted on a movable contact member 19. At its end remote from the movable contact 18, the contact member 19 is formed into a hook portion 20 which loosely fits about a stud 21 formed in a link member 22.

For moving the contact member 19 between the open circuit and closed circuit positions I provide a contact arm 23. One end of the contact arm is provided with an opening 24 which fits about a pin 25 formed on an intermediate portion of contact member 19, while an intermediate portion of contact arm 23 is formed with an opening 26 which closely fits about the stud 21 formed in link member 22. A coil spring 27 is disposed between an intermediate point on the contact member 19 and in recess or abutment formed in the molded casing 11. The spring thus biases the contact member 19 for rotation about the pivot point provided by the pin 25 and opening 24.

For manually moving the contact member 19 and contact arm 23 between the open circuit and closed circuit positions I provide a manually operable, rotary handle 29. The handle 29 is formed with an arcuate portion 30 which is mounted in a slot 30a formed in the casing 11 between one casing wall 30b and a raised portion 30c. A lever portion 31 extends radially through an aperture in the casing to provide an element which the user may grasp to. manually operate the mechanism. The end of the arcuate portion 30 more remote from the lever portion 31 is formed with a pin 32 which is received in an elongated slot 33 provided in one end 34 of link member 22. This construction of the handle 29 and link member 22 provides a manual operating mechanism which enables the circuit breaker to be constructed with its greater dimension in the front-to-rear direction.

In order to guide the contact arm 23 for pivoting or rocking movement as the circuit breaker mechanism is opened and closed, the stud 21 is received in arcuate slot 35 formed in the casing. Additionally the end of the contact arm 23 remote from the opening 24 is formed with a tab 36 which engages a shoulder 37 formed adjacent one end of an intermediate latch member 38. Thus the contact arm 23 and contact member 19 are mounted for pivotal or rocking motion within the casing 11 as they are moved by the link member 22 for opening and closing the circuit.

To manually move the circuit breaker mechanism from the open circuit position (shown in FIG. 1) to the closed circuit position (shown in FIG. 2) the handle 29 is rotated in a clockwise direction thereby moving link member 22, contact arm 23, and contact member 19 in a clockwise direction with contact arm 23 rotating about the fulcrum provided by the engagement of tab 36 with shoulder 37. The spring 27 holds hook portion 20 of contact member [19 against stud 21 until contact 18 engages contact 17, after which further movement of handle 29 is transferred to contact member 19 through link member 22 and pin 25 and causes hook portion 20 to move away from stud 21. The spring 27, being compressed, biases the contact member 19 for rotation about the pivot point provided by pin 25 and opening 24, thus ensuring suflicient contact pressure between contact 18 and contact 17. The mechanism is locked in the closed circuit position by the engagement of the end 34 of link 22 with a cam surface 39 formed in casing 11.

To manually move the circuit breaker mechanism to the open circuit position handle 29 is rotated in a counterclockwise direction, thereby rotating link member 22 in the counterclockwise direction until the end 34 of the link member is disengaged from the cam surface 39. Further counterclockwise movement of the handle 29 causes the spring 27 to initially rotate contact member 19 in a clockwise direction about the pivot point provided by pin 25 and opening 24 until hook portion 20 engages stud 21, 'after which spring 27 eifectively locks contact member 19 and contact arm 23 together for unitary movement to the open circuit position. During the movement of the contact arm 23 and contact member 19 to the open circuit position the contact arm 23 again pivots about the fulcrum provided by the tab 36 engaging the shoulder 37.

The intermediate latch or pivot support member 38 is mounted on a pin 40 formed in the casing 11 and is normally held in the position shown in FIGURES l and 2 by means of a current-responsive mechanism indicated generally at 41. In order to retain the intermediate latch member in this position, an electromagnet 42 is mounted in the casing and supports an armature or latch 43. One end of the armature 43 is formed with an opening 44 which normally engages an abutment 45 formed in the end of intermediate latch member 38 remote from the shoulder 37. The engagement of the armature 43 with the abutment 45 normally retains the intermediate latch member 38 in the position shown in FIGURES 1 and 2 so that the contact arm 23 may pivot or rock about the tulcrum provided by engagement of the tab 36 with the shoulder 37 as the manually operable handle is rotated to move the circuit breaker mechanism between open circuit and closed circuit positions.

In order to automatically open the circuit breaker mechanism in response to a relatively low overcurrent condition, a bimetal member 46 is provided adjacent the electromagnet. One end of the bimetal member is conductively mounted upon load terminal 14. A flexible lead 47 electrically connects the bimetal to the hook portion 20 of contact member 19. The bimetal 46 is connected to the armature 43 for disengaging the armature from the abutment 45 by a thermal-deflection coupling member 48 which is slidably mounted on the armature 43. One end 49 of the coupling member engages bimetal member 46 while the other end 50 is received in a slot 51 formed in the armature 43. The coupling member 48 is provided with 'a shoulder 52 which engages the armature 43 in order to move the armature in response to movement of the bimetal member 46.

An armature spring 53 is carried on the armature 43 and bears against the coupling member 48, thus forcing it into contact with bimetal member 46. One end 54 of the spring 53 is received in the recess 55 formed in the intermediate latch member adjacent the abutment 45.

In order to automatically open the circuit breaker mechanism in response to a relatively high overcurrent condition, the armature 43 is formed with an armature extension 56 at the end of the armature remote from the opening 44. The armature extension 56 is disposed adjacent a magnetic pole face 57 formed in the electromagnet 42. When the circuit breaker mechanism is in the closed circuit position (shown in FIG. 2), current flows through line terminal clip 12, the contacts 17 and 18, contact member 19, flexible lead 47, bimetal 46, and load terminal member 14. Since the bimetal 46 passes through the U-shaped magnet 42, it acts as an energizing winding therefor. Thus, in the event of a relatively high overcurrent condition, the electromagnet 42 attracts armature extension 56 to the magnetic pole face 57, rotating the armature 43 in a counterclockwise direction and disengaging the opening 44 from the abutment 45 of the intermediate latch member 38. When this occurs the force exerted upon the intermediate latch member 38 by spring 27 through the contact arm 23 causes the intermediate latch member 38 to rotate in a counterclockwise direction until the tab 36 of contact arm 23 is disengaged from the shoulder 37. The tab 36 then strikes the extension 22a of the link member 22, rotating link member 22 in a counterclockwise direction, thus releasing the end 34 of link member 22 from the cam surface 39. The spring 27 then rotates contact member 19 about the pivot point provided by pin 25 and opening 24 until the hook portion 20 engages the stud 21, after which the spring 27 moves the contact member 19 and contact arm 23 as a unit to the circuit open position (shown in FIG. 1).

As the intermediate latch member 38 is rotated in the counterclockwise direction, it deflects the armature spring 53 and, upon completion of the movement of the circuit breaker mechanism to the open circuit position, the armature spring returns the intermediate member to the position shown in FIGURES 1 and 2 so that the circuit breaker is set for manual closing.

In the event of a relatively small overcurrent condition the 'bimetal member 46 deflects in a counterclockwise direction and moves the coupling member 68 in a counterclockwise direction. Since the shoulder 52 engages the armature 43, the armature is also carried in the counterclockwise direction. This disengages the opening 44 from the abutment 45 andfrees the intermediate latch member 38. Then, in the same manner as in the relatively high overcurrent situation, the intermediate memher is rotated in a counterclockwise direction and the circuit breaker mechanism is moved to the open circuit position, after which the intermediate latc'h member 38 is returned to the position shown in FIGURES 1 and 2 to set the circuit breaker from manually closing.

Thus, the armature spring 53 serves two purposes. First, by hearing against the coupling member 48, it ensures that the coupling member is retained in contact with the bimetal member 46 to couple the bimetallic member to the latch member regardless of their original spacing, within a certain range of variation. It also functions to return the intermediate latch member 38 to the position shown in FIGURES 1 and 2 after each automatic trip operation in order to relatch the circuit breaker for manually closing. It will be noted that the circuit breaker mechanism is self-resetting in that it is ready for manual closing after each opening operation, whether it be a manual opening or an automatic opening operation.

It will be understood that the magnetic operation in response to the relatively high overcurrent condition and the thermal operation in response to a relatively low overcurrent condition are not mutually exclusive and automatic tripping of the circuitbreaker mechanism may occur as a result of the combination action of the electromagnet 42 and bimetal 46.

Understanding of the operation of the circuit breaker mechanism will be assisted by reference to FIGURES 4, 5, 6, and 7 in which the various elements of the circuit breaker mechanism have been drawn in elementary form and numbered with primes (such as 19, 20, 21', etc.) to indicate their correspondence to elements of the circuit breaker.

In FIGURE 4 (which shows the open circuit position) the spring 27' forces the end 20 of contact member 19' against contact arm 23 so that the contact member 19' and the contact arm 23 move as a unit.

In FIGURE 5 the link member 22 has moved the contact arm 23' and contact member 19' to a position where the contact 18 is just touching the contact 17 and the spring 27 is still retaining the end 20 against contact arm 23'.

FIGURE 6 shows that further movement of link member 22 causes contact arm 23' to act through pin 25' to force contact member 19' to rock about contact 18 so as to disengage end portion 20' from contact arm 23' and further compress spring 27'. In this position, the force exerted on contact member 19' by spring 27 now biases contact member 19' for rotation clockwise, as viewed, about pin 25' to maintain contact pressure between con- 6 tacts 18' and 17'. It will be noted that the direction of bias of the spring 27 on the movable contact 18' is reversed between FIGS. 5 and 6.

In FIGURE 7 the intermediate latch member 38' has been moved to release the left-hand end of the contact arm 23' to trip the circuit breaker mechanism, and spring 27 has rotated contact member 19' about pin to bring end portion 20' into contact with contact arm 23' and move contact arm 23' and contact member 19' as a unit to the open circuit position. It should be noted that this action takes place even though the operating member 22' is manually held in closed circuit position. When the member 22 is unrestrained, the spring urges the contact assembly upwards, moving the handle back toward OFF position. At the same time, the end of contact member 19 engages surface 11A of the case, and thereafter the spring 27' rocks the contact assembly about this engagement, raising the opposite end to a position where it can once again be engaged by the intermediate latch member or pivot support 38'. Thus the mechanism is self-resetting.

While I have shown a particular embodiment of my invention, it will be obvious that many modifications will occur to those skilled in the art. For instance it is only required that the spring 27 bear against the contact member 19 at some point between the pin 25 and the end 20. Also, it is not necessary that the hook portion 20 extend around stud 21, in this regard all that isrequired is that the contact member 19 be formed to engage contact arm 23 so that rotation of the contact member with relation to the contact arm is limited in the clockwise direction as viewed, so that the spring 27 will move the contact arm 23 and contact member 19 as a unit after such limit is reached.

Further, as indicated in FIGS. 4-7, it is not required that the link member 22 act upon the contact arm 23 at the same point as the hook portion 20 engages the contact 23; in this regard, all that is required is that link member 22 act upon the contact arm 23 at some point between the intermediate latch member 38 and the line of action of the spring 27.

While I have described a preferred embodiment of my invention by way of illustration, other modifications will appear to those skilled in the art, and I thereforeintend by the appended claims to cover all such modifications as fall within the true scope and spirit of my invention.

What I claim as new and desire to be secured by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

(a) an insulating casing,

(b) a stationary contact supported in said casing,

(c) a contact arm in said casing having first and second end portions,

(d) latching means carried by said casing and releasably supporting said first end portion of said contact arm for pivotal movement of said contact arm thereabout between open and closed circuit positions,

(e) a movable contact member pivotally supported on said contact arm at a pivot point adjacent said second end portion,

(f) said contact member including a first section extending from said pivot point toward said first end portion of said contact arm and a second section extending from said pivot point away from said first end portion of said contact arm,

(g) a spring mounted between said casing and said first section of said contact member to bias said contact member for rotation about said pivot point,

(h) stop means carried by said contact arm for limiting rotation of said contact member about said pivot point, said spring moving said contact arm and said contact member thereafter as a unit toward the open circuit position,

- (i) manually operable means supported in said casing and acting on said contact arm,

(j) said manually operable means for pivoting said contact arm and said contact member as a unit about said latching means until said second section of said contact member engages said stationary contact, and for thereafter moving said first section of said contact member away from said stop means and stressing said spring to urge said second section of said contact member into engagement with said stationary contact.

2. An electric circuit breaker as described in claim 1 wherein said manually operable means includes cam means positioned between said contact arm and said casing for releasably securing said contact arm and said contact member in the closed circuit position.

3. An electric circuit breaker as described in claim 1 futrher including a current-responsive means supported in said casing and responsive to a predetermined overcurrent condition to release said latching means for releasing said first end portion of said contact arm, said spring then rotating said contact member about said pivot point until said contact member engages said stop means, said spring thereafter moving said contact arm and said contact member as a unit toward the open circuit position.

4. An electric circuit comprising:

(a) an insulating casing,

(b) a stationary contact supported in said casing,

(c) a contact arm in said casing having first and second end portions,

(d) latching means carried by said casing and releasably supporting said first end portion of said contact 'arm for pivotal movement of said contact arm thereabout between open and closed circuit positions,

(e) a movable contact member pivotally supported on said contact arm at a pivot point adjacent said second end portion,

(f) said contact member including a first section extending from said pivot point toward said first end portion of said contact arm and a second section extending from said pivot point away from said first end portion of said contact arm,

(g) a spring mounted between said casing and said first section of said contact member to bias said contact member for rotation about said pivot point,

(h) stop means carried by said contact arm for limiting rotation of said contact member about said pivot point, said spring moving said contact arm and said contact member thereafter as a unit toward the open circuit position,

(i) manually operable means supported in said casing and acting on said contact arm,

(j) said manually operable means moving in a first direction for pivoting said contact arm and said contact member as a unit about said latching means until said second section of said contact member engages said stationary contact, and for thereafter moving said first section of said contact member away from said stop means and stressing said spring to urge said second section of said contact member into engagement with said stationary contact,

(k) said manually operable means moving in a second direction stressing said spring for pivoting said contact member about said pivot point until said first section of said contact member engages said stop means, and for thereafter stressing said spring for pivoting said contact arm and said contact member as a unit about said latching means toward the open circuit position.

5. An electric circuit breaker comprising:

(a) an insulating casing,

(b) a stationary contact supported in said casing,

(c) a contact arm in said casing having first and second end portions and an opening intermediate said end portions,

(d) latching means carried by said casing and releasably supporting said first end portion of said contact ti arm for pivotal movement of said contact arm thereabout between open and closed circuit positions,

(e) a movable contact member pivotally supported on said contact arm at a pivot point adjacent said second end portion,

(f) said contact member including a first section extending from said pivot point toward said first end portion of said contact arm and a second section extending from said pivot point away from said first end portion of said contact arm,

(g) a spring mounted between said casing and said first section of said contact member to bias said contact member for rotation about said pivot point,

(h) an operating member including a body portion rotatably supported in said casing and a handle portion extending through said casing for manual movement between open and closed circuit positions,

(i) a link member having a first end portion secured to said body portion of said operating member and including a stud spaced from said first end portion of said link member,

(j) said stud being received in said opening in said contact arm with a close sliding fit and extending through said opening for selective engagement by said contact member for limiting rotation of said contact member about said pivot point, said spring moving said contact arm and said contact member as a unit toward the open circuit position,

(k) manual movement of said operating member from the open circuit position toward the closed circuit position moving said stud for pivoting said contact arm and said contact member as a unit about said latching means until said second section of said contact member engages said stationary contact, and for thereafter moving said first section of said contact member away from said stud and stressing said spring to urge said second section of said contact member into engagement with said stationary contact,

(1) manual movement of said operating member from the closed circuit position toward the open circuit position stressing said spring for pivoting said contact member about said pivot point until said first section of said contact member engages said stud, and for thereafter stressing said spring to move said contact arm and said contact member as a unit toward the open circuit position.

6. An electric circuit breaker as described in claim 5 wherein said casing includes a cam surface, the movement of said operating member from the open circuit position toward the closed circuit position also moving said first end portion of said link member to engage said cam surface for releasably locking said contact arm and said contact member in the closed circuit position.

7. For use in an electric circuit breaker including an insulating casing, a stationary contact supported in the casing, and a movable contact structure mounted in the casing; a latch mechanism including:

(a) a latch member mounted in the casing for controlling movement of the movable contact structure,

(b) a bimetal member mounted in the casing in spaced relationship with said latch member and responsive to an overcurrent condition to eifect movement of said latch member,

(c) a coupling member slidably mounted on said latch member and extending into engagement with said bimetal member,

(d) spring means mounted on said latch member and acting on said coupling member, said spring means biasing said coupling member to engage said bimetal member for automatic compensation for variations in the relative positions of said bimetal member and said latch member.

8. For use in an electric circuit breaker including an insulating casing, a stationary contact supported in said casing, and a movable contact mechanism supported in 9, said casing, said mechanism having a member releasable to automatically open said contact mechanism; a latch mechanism comprising:

(a) a latch member mounted in said casing for releasably engaging said releasable member,

(b) an elongated bimetal member mounted in said casing in spaced parallel relation with said latch member, said bimetallic member being responsive to overcurrent conditions in said circuit breaker,

(c) a coupling member slidably mounted on said latch member and including a portion extending into engagement with the end of said bimetal member,

(d) biasing means biasing said coupling member for longitudinal movement along said latch member in a direction parallel to said :bimetal member, said portion of said coupling member extending into engagement with the end of said bimetal member extending at an angle thereto substantially less than 90, whereby said coupling member serves to couple said bimetal member to said latch member despite predetermined variations in the relative positions thereof.

9. For use in an electric circuit breaker including an insulating casing, a stationary contact supported in the casing, and a movable contact structure mounted in the casing; a latching mechanism including:

(a) an intermediate latch member supported in the casing intermediate its ends,

(b) a first end portion of said intermediate member releasably supporting a portion of the movable contact mechanism for manual movement thereabout of the movable contact structure between open and closed circuit positions,

(c) a latch member movably supported in said casing and engaging a second end portion of said intermediate member to retain said intermediate member in a first position for supporting the movable contact structure,

(d) a bimetal member supported in said casing in spaced relationship with said latch member,

(e) a coupling member slidably mounted on said latch member and extending into engagement with said bimetal member,

(f) a spring member having one end mounted on said latch member and the other end engaging said second end portion of said intermediate member,

(g) a portion of said spring member intermediate its ends acting on said coupling member biasing said coupling member to engage said bimetal member,

(h) said bimetal deflecting in response to an overcurrent condition to move said latch member out of engagement with said second end portion of said intermediate member to release said intermediate latch member for movement to a second position freeing the movable contact structure to move automatically to the open circuit position,

(i) said spring returning said intermediate member to its first position after the movable contact structure has moved to the open circuit position.

10. For use in an electric circuit breaker including an insulating casing, a stationary contact supported in the casing and a movable contact structure mounted in the casing; a latching mechanism including:

(a) an intermediate latch member supported in the casing intermediate its ends,

(b) a first end portion of said intermediate latch member releasably supporting the movable contact structure for manual movement thereabout of the movable contact structure between open and closed circuit positions,

(c) a latch member movably supported in said casing and engaging a second end portion of said intermediate latch member to retain said intermediate latch member in a first position for supporting the movable contact structure,

(d) a bimetal member supported in said casing in spaced relationship with said latch member,

(e) a coupling member slidably mounted on said latch member and extending into engagement with said bimetal member,

(f) a spring member having one end mounted on said latch member and the other end engaging said second end portion of said intermediate latch member,

(g) a portion of said spring intermediate its ends acting on said coupling member biasing said coupling member to engage said bimetal member and to couple said bimetal member to said latch member despite predetermined variations in the positions thereof,

(h) an electromagnet positioned in the casing adjacent said latch member, a

(i) said bimetal member deflecting in response to a relatively low overcurrent condition to move said latch member out of engagement with said second end portion of said intermediate member to release said intermediate member for movement to a second position freeing the movable contact structure to move automatically to the open circuit position,

(j) said electromagnet being effective upon a relative high overcurrent condition to move said latch memberout of engagement with said second end portion of said intermediate member to release said intermediate member for movement to a second position freeing the movable contact structure to move automatically to the open circuit position,

(k) said spring returning said intermediate latch member to its first position after the movable contact structure has moved to the open circuit position.

11. An electric circuit breaker comprising:

(a) an insulating casing,

3 (b) a stationary contact supported in said casing,

(c) a contact arm in said casing having first and second end portions and an opening intermediate said end portions,

(d) latching means carried by said casing and releasably supporting said first end portion of said contact arm for pivotal movement of said contact arm thereabout between open and closed circuit positions,

: (e) a movable contact member pivotally supported on said contact arm at a pivot point adjacent said second end portion,

(f) said contact member including a first section extending from said pivot point toward said first end portion of said contact arm and a second section extending from said pivot point away from said first end portion of said contact arm,

(g) a spring mounted between said casing and said first section of said contact member to bias said contact member for rotation about said pivot point,

(h) an operating member including a body portion rotatably supported in said casing and a handle portion extending through said casing for manual movement between open and closed circuit positions,

I (i) a link member having a first end portion secured to said body portion of said operating member and V including a stud spaced from said first end portion of said link member,

. (j) said stud beingclosely received in said opening in said contact arm and extending through said opening for selective engagement by said first section of said contact member for limiting rotation of said contact member about said pivot point, said spring moving said contact arm and said contact member as a unit toward the open circuit position,

(k) manual movement of said operating member from the open circuit position toward the closed circuit position moving said stud for pivoting said contact arm and said contact member as a unit about said latching means until said second section of said contact member engages said stationary contact, and

for thereafter moving said first section of said contact member away from said stud and causing said spring to bias said contact member in a direction to urge said second section of said contact member into engagement with said stationary contact,

(1) said casing including a cam surface, the movement of said operating member from the open circuit position toward the closed circuit position also moving said first end portion of said link member to engage said cam surface for releasably locking said contact arm and said contact member in the closed circuit position,

(in) manual movement of said operating member from the closed circuit position toward the open circuit position stressing said spring for pivoting said contact member about said pivot point until said first section of said contact member engages said stud,

-' and for thereafter stressing said spring to move said contact arm and said contact member as a unit toward the open circuit position, and

(n) a current-responsive means supported in said casing and responsive to a predetermined overcurrent condition to release said latching means for releasing said first end portion of said contact arm, said spring then rotating said contact member about said pivot point until said first section of said contact member engages said stud, said spring thereafter moving said contact arm and said contact member as a unit toward the open circuit position.

12. An electric circuit breaker comprising:

(a) an insulating casing,

(b) a stationary contact supported in said casing,

(c) a contact arm in said casing having first and second end portions and an opening intermediate said end portions,

(d) a movable contact member pivotally supported on said contact arm at a pivot point adjacent said second end portion,

(e) said contact member including a first section extending from said pivot point toward said first end portion of said contact arm and a second section extending from said pivot point away from said first end portion of said contact arm,

(f) a first spring mounted between said casing and said first section of said contact member to bias said contact member for rotation about said pivot point,

(g) an operating member including a body portion rotatably supported in said casing and a handle portion extending through said casing for manual movement between open and closed circuit positions,

(h) a link member having a first end portion secured to said body portion of said operating member and including a stud spaced from said first end portion of said link member,

(i) said stud being closely received in said opening in said contact arm and extending through said opening for selective engagement by said contact member for limiting rotation of said contact member about said pivot point, said first spring moving said contact arm and said contact member as a unit toward the open circuit position,

(j) an intermediate member supported in the casing intermediate its ends,

(k) a first end portion of said intermediate member releasably supporting said first end portion of said contact arm for pivotal movement of said contact arm thereabout between open and closed circuit positions,

(l) a latch member movably supported in said casing and engaging a second end portion of said intermediate member to retain said intermediate member in a first position for supporting said contact arm,

(in) a bimetal member supported in said casing in spaced relationship with said latch member,

(n) an adjusting member slidably mounted on said latch member and extending into engagement with said bimetal member,

(0) a second spring member having one end mounted on said latch member and the other end engaging said second end portion of said intermediate member,

(p) a portion of said second spring intermediate its ends acting on said adjusting member biasing said adjusting member to engage said bimetal member,

(q) an electromagnet positioned in the casing adjacent said latch member,

(r) manual movement of said operating member from the open circuit position toward the closed circuit position moving said stud for pivoting said contact arm and said contact member as a unit about said intermediate member until said second section of said contact member engages said stationary contact, and for thereafter moving said first section of said contact member away from said stud and stressing said first spring to urge said second section of said contact member into engagement with said stationary contact, 1}

(s) said casing including a cam surface, the movement of said operating member from the open circuit position toward the closed circuit position also moving said first end portion of said link member to engage said cam surface for releasably locking said contact arm and said contact member in the closed circuit position,

(t) manual movement of said operating member from the closed circuit position toward the open circuit position stressing said first spring for pivoting said contact member about said pivot point un-til said first section of said contact member engages said stud, and for thereafter stressing said spring to move said contact arm and said contact member as a unit toward the open circuit position,

(u) said bimetal member deflecting in response to a relatively low overcurrent condition to move said latch member out of engagement with said second end portion of said intermediate member to release said intermediate member for movement to a second position freeing said contact arm and said contact member to move automatically to the open circuit position, i

(v) said electromagnet being effective upon a relative high overcurrent condition to move said latch member out of engagement with said second end portion of said intermediate member to release said intermediate member for movement to a second position freeing said contact arm and said contact member to move automatically to the open circuit position,

(w) said second spring returning said intermediate member to its first position after the said contact arm and said contact member have moved to the open circuit position.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

A, LEWITT R, m e 

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) AN INSULATING CASING, (B) A STATIONARY CONTACT SUPPORTED IN SAID CASING, (C) A CONTACT ARM IN SAID CASING HAVING FIRST AND SECOND END PORTIONS, (D) LATCHING MEANS CARRIED BY SAID CASING AND RELEASABLY SUPPORTING SAID FIRST END PORTION OF SAID CONTACT ARM FOR PIVOTAL MOVEMENT OF SAID CONTACT ARM THEREABOUT BETWEEN OPEN AND CLOSED CIRCUIT POSITIONS, (E) A MOVABLE CONTACT MEMBER PIVOTALLY SUPPORTED ON SAID CONTACT ARM AT A PIVOT POINT ADJACENT SAID SECOND END PORTION, (F) SAID CONTACT MEMBER INCLUDING A FIRST SECTION EXTENDING FROM SAID PIVOT POINT TOWARD SAID FIRST END PORTION OF SAID CONTACT ARM AND A SECOND SECTION EXTENDING FROM SAID PIVOT POINT AWAY FROM SAID FIRST END PORTION OF SAID CONTACT ARM, (G) A SPRING MOUNTED BETWEEN SAID CASING AND SAID FIRST SECTION OF SAID CONTACT MEMBER TO BIAS SAID CONTACT MEMBER FOR ROTATION ABOUT SAID PIVOT POINT, (H) STOP MEANS CARRIED BY SAID CONTACT ARM FOR LIMITING ROTATION OF SAID CONTACT MEMBER ABOUT SAID PIVOT POINT, SAID SPRING MOVING SAID CONTACT ARM AND SAID CONTACT MEMBER THEREAFTER AS A UNIT TOWARD THE OPEN CIRCUIT POSITION, (I) MANUALLY OPERABLE MEANS SUPPORTED IN SAID CASING AND ACTING ON SAID CONTACT ARM, (J) SAID MANUALLY OPERABLE MEANS FOR PIVOTING SAID CONTACT ARM AND SAID CONTACT MEMBER AS A UNIT ABOUT SAID LATCHING MEANS UNTIL SAID SECOND SECTION OF SAID CONTACT MEMBER ENGAGES SAID STATIONARY CONTACT, AND FOR THEREAFTER MOVING SAID FIRST SECTION OF SAID CONTACT MEMBER AWAY FROM SAID STOP MEANS AND STRESSING SAID SPRING TO URGE SAID SECOND SECTION OF SAID CONTACT MEMBER INTO ENGAGEMENT WITH SAID STATIONARY CONTACT. 